Snow and ice removal system for an antenna

ABSTRACT

Water is pumped for a predetermined time at a given rate from a water tank, burried below ground level to prevent freezing, to a plurality of spray nozzles appropriately positioned about the reflecting surface of an antenna so that the water discharged from the plurality of nozzles completely covers the reflecting surface to remove accumulations of ice and/or snow thereon. Under extreme temperatures conditions, the water can be mixed with an appropriate amount of anti-freeze solution or preheated. The Water distribution system includes a flexible portion adjacent the bottom of the reflecting surface with sufficient slack to enable azimuth and elevation motion of the antenna.

United States Patent Erdmann 1 July 4, 1972 SNOW AND ICE REMOVAL SYSTEM FOR AN ANTENNA M. Otto Erdmann, Denville, NJ.

International Telephone and Telegraph Corporation, Nutley, NJ.

Filed: Nov. 25, 1970 App]. No.: 92,719

Inventor:

Assignee'.

References Cited UNITED STATES PATENTS 8/1952 Garland ..62/282 X 8/1954 Zellner..... ....62/282 X 1/1944 Wiegand.. ..62/282 3/1876 Lount ..62/282 X spasm FOO ruvc;

Primary Examiner-Richard A. Schacher Assistant Examiner-Thomas C. Culp Jr.

Att0meyC. Cornell Remsen, Jr., Walter J. Baum, Paul W. Hemminger, Charles L. Johnson, Jr., Philip M. Bolton, Isidore Togut, Edward Goldberg and Menotti J. Lombardi, Jr.

[57] ABSTRACT Water is pumped for a predetermined time at a given rate from a water tank, burried below ground level to prevent freezing, to a plurality of spray nozzles appropriately positioned about the reflecting surface of an antenna so that the water discharged from the plurality of nozzles completely covers the reflecting surface to remove accumulations of ice and/or snow thereon. Under extreme temperatures conditions, the water can be mixed with an appropriate amount of antifreeze solution or preheated. The Water distribution system includes a flexible portion adjacent the bottom of the reflecting surface with sufficient slack to enable azimuth and elevation motion of the antenna.

9 Claims, 2 Drawing Figures S04 UT/ON TANK GROUND L 5 V6 L P'A'TENTEnJuL 4 1972 3,674,215

24 8 m a? H 34 fi a3 2 M a? 87 816 a? 24 23 23 9 24 x E26 '24 33 Z as 24 87 E29 27 34 2? Wm E E7 A f 24 e4 5 g g v V y -FREZ SPREAD 7 fi & {IT/OM GROUND Fm mm? -11; mmk gun/5L AXUIUARY mama WWW: WATER I=== PUMW 53 l; souncs w W f7 INVENTOR I 2 86 M. arm mama AMI P'A'TENIEUJUL d m2 NVENTOR W0 M SNOW AND ICE REMOVAL SYSTEM FOR AN ANTENNA BACKGROUND OF THE INVENTION During normal operation of a satellite communications earth station or a radio telescope station, a minimum value of signal strength must be maintained for adequate transmission and reception. Environmental disturbances such as snow and ice drastically reduce reception capabilities of an antenna system as the new propagation media provided by the accumulation of ice or snow which gradually builds up the large exposed surface of the main reflector.

As a solution to snow and ice removal, the following techniques have been used in many instances in the past.

Commercially obtained electric stn'p heaters are cemented to the rear surface of the main reflector at close intervals and are then embedded in a poured insulator, such as polyurethane, so as to prevent heat loss to the air and provide efficient conductivity to the main aluminum reflector surface to be heated. Several independent circuits are thermostatically controlled either separately or in combination to. melt existing snow and ice, or to prevent their formation and accumulation. Disadvantages of this type of ice and snow removal system is the l high initial installation cost of approximately $100,000 for a 100 foot diameter reflector; (2) high operating cost since the device draws approximately 800 kilowatts of power; (3) due to the high power drain, either a large source must be provided initially, or a separate power system must be installed; (4) in the event of power failure, the device is rendered inoperative; and (5) short or open circuits are common, thereby reducing the overall device effectiveness.

The use of heated air consists of enclosing the rear of the main reflector with sheet metal to form a large baffle-duct system. The enclosed air is then heated and circulated through this enclosed volume by blowers. Convection heat transfer then provides snow-ice removal as desired. The disadvantage of this arrangement is (1) high initial installation cost of approximately $150,000 for a 100 foot diameter reflector; (2) high operating cost since a large volume of air must be heated and circulated; (3) start up times are excessively long, yet continuous operation is cost prohibitive; 4) a separate fuel supply is required; (5) the baffle enclosure is heavy and contributes to the static deformations of the main reflector, therefore additional stiffness must be built into the reflector design; and (6) due to the large mass of air involved, temperatures are not uniformly maintained throughout the arrangement.

An arrangement wherein the antenna is totally enclosed within a radome to which snow and ice will not adhere. The disadvantage of this arrangement is (1) high initial installation cost of approximately $125,000 for a 100 foot diameter antenna; 2) the radome is susceptible to damage; and (3) the inherent attenuation loss due to the material and overlapping seam incongruities exists.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved snow and/or ice removal system for an antenna incorporating a reflecting surface.

Another object of the present invention is to provide a snow and/or ice removal system for an antenna having a reflecting surface which overcomes the disadvantages of the prior art snow and/or ice removal systems mentioned hereinabove.

A feature of the present invention is the provision of a snow and ice removal system for an antenna having a reflecting surface comprising a first reservoir of fluid; a plurality of nozzles disposed adjacent the reflecting surface; and a fluid distribution system connecting the first reservoir to the plurality of noules to supply the fluid to the polarity of nozzles; the nozzles being appropriately disposed with respect to the reflecting surface and the flow of the fluid in the distribution system controlled to insure that the reflecting surface is completely covered by the fluid discharged from the plurality of nozzles to thereby remove snow and ice from the reflecting surface.

BRIEF DESCRIPTION OF THE DRAWING The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a rear elevational view of an antenna having a reflecting surface illustrating schematically the snow and ice removal system incorporated therewith in accordance with the principles of the present invention; and

FIG. 2 is a side elevational view of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the description of the preferred embodiment of the invention presented hereinbelow certain values of diameters and pressure are given of a reduction to practice of the present invention, but it is to be understood that these values may be varied to meet specific specifications of other antenna structures and still be within the scope of the present invention.

The snow and ice removal system of the present invention is a simple, inexpensive system for removing or preventing the accumulation of ice and snow on the primary reflecting surface of a large ground communications antenna used with synchronous satellites.

Referring to FIGS. 1 and 2, there is illustrated therein an antenna 1 having a main reflector 2 having a diameter of 98.4 feet and a feed horn assembly 3 appropriately associated therewith. A plurality of nozzles 4 (FIG. 2) are arranged in five groups of three nozzles each as illustrated at 5, 6, 7, 8 and 9. A sixth group of five nozzles 40 is arranged below the feed horn 3 as illustrated at 10 (FIG. 2). Nozzles 4 and 4a may be Monarch flat spray nozzles.

A first reservoir of fluid, such as water tank 11 having a replenishable capacity of 300 gallons: is located sufficiently below ground level to prevent freezing. A fluid distribution system is connected between tank 11 and the spray nozzles 4 and 4a to supply the fluid, in the form of water, to these various nozzles. The fluid distribution system includes a motorpump assembly 12 having its suction input 13 connected to tank 1 l by a 4 inch diameter galvanized pipe 14. The output of assembly 12 has coupled thereto a 4 inch diameter galvanized pipe 15 which terminates in a coupling 16. Connected to coupling 16 is a 4 inch diameter flexible pipe 17 with suflicient slack, such as provided by loop 18, to allow for normal antenna motion in both azimuth and elevation. Flexible pipe 17 may be formed of polyethylene. Pipe 17 is terminated in a manifold 19 formed of 3 inch diameter galvanized pipe disposed about the antenna structure hub 20. Extending radially from manifold 19 are 5 1% inch diameter flexible pipes 21a, 21b, 21 c, 21d and 21e, made for instance of polyethylene, spaced at an angle of approximately 45 and secured to the radial beams 22a, 22b, 22c, 22d and 22e of the reflector. Each of the pipes 21 are terminated in a branching portion to feed water to each nozzle of the groups of three nozzles. These branching portions of the distribution system are composed of 1 inch diameter flexible pipes 23 and 24 with pipes 24 being connected directly to nozzles 4. Also coupled to manifold 19 is the group of five spray nozzles 4a extending through the reflecting surface and disposed below the feed horn assembly 3. This group of five spray nozzles is fed from a branching portion of the distribution system similar to that discussed and illustrated with respect to nozzles 4.

The distribution of the five groups of three nozzles 4 about the periphery of surface 2 and the one group of five nozzles 40 disposed below assembly 3 as illustrated in FIGS. 1 and 2 provides complete coverage of the surface area of surface 2.

Provisions are provided to drain that. portion of the distribution system above coupling 16 by disconnecting pipe 17 from coupling 16 and providing a pitch toward manifold 19 in pipes 21a and 21e.

Motorpump assembly 12 includes a 60 horse power motor with a pumping capacity of 400 gallons per minute (GPM) which moves the water from tank 11 up 120 feet to the spray nozzles. The pump assembly 12 operates at 2,850 revolutions per minute and produces a total dynamic head of 197 feet which is equivalent to 85 pounds per square inch. As a consequence the water discharged from nozzles 4 and 4a is under pressure due to the operation of assembly 12 and the diameter reduction of the pipes in the distribution system.

The system as described is designed to operate for a 10 minute period during which time snow and/or ice removal or prevention is achieved. Where longer periods of operation are required the water tank 11 is replenished by a auxiliary water source 25, such as another storage tank, a lake, a pond or a stream by means of motor-pump assembly 26. For the extended operating period the water of tank 11 from source 25 through means of assembly 26 must be replenished at a'rate of at least 400 GPM. All of the nozzles 4 and 4a are designed and adjustable in position with throttling being provided by valves 27 and 28 to give equal flow at varying pressures, thereby providing uniform coverage across the reflector surface.

Where geographical locations permit, such as in Madrid, Spain, the system of this invention uses only available water containing no special additives since the ambient temperature during snow and/or ice precipitation is not drastic. For use in more extreme environments producing a heavy snow and/or ice accumulation, or in extra cold temperatures, the water of tank 11 may be pre-heated such as by source 29 and/or antifreeze solutions, such as ADF II and USAR 35 manufactured by the Union Carbide Corporation, may be added from tank 30 to tank 1 l in predetermined amounts.

The above-described system is considered to be an improvement in antenna snow removal and/or de-icing system due to the following advantages: (1) initial installation cost is relatively low. A system has been installed for less than $25,000 including $15,000 of material cost and $10,000 of installation cost; (2) operational costs are low since available water is the prime constituent; (3) a prime power failure will not affect the operation of the device since a 40 kilovolt ampere standby generator can be used; (4) start up time is short; (5) the weight of the ice and/or snow removal system of this invention is light, therefore, deformations of the reflector is not a problem and design stiffness is not required; (6) uniform and efi'ective coverage of the reflector surface is provided; and (7) optional methods of increasing operational efficiency, such as heating the water and/or adding an anti-freeze source to the water, is available.

While I have described above the principles of my invention in connection with specific apparatus it is to be more clearly understood that this description is made only by way of example and not as a limitation to the scope as set forth in the objects thereof and in the accompanying claims.

I claim:

1. A snow and ice removal system for an antenna having a reflecting surface comprising:

a first reservoir of fluid;

a plurality of nozzles disposed adjacent said reflecting surface; and

a fluid distribution system connecting said first reservoir to said plurality of nozzles to supply said fluid to said plurality of nozzles;

said nozzles being appropriately disposed with respect to said reflecting surface and the flow of said fluid in said distribution system being controlled to ensure that said reflecting surface is completely covered by said fluid discharged from said plurality of nozzles to thereby remove snow and ice from said reflecting surface; and

said distribution system including a portion of flexible pipe with sufl'icient slack to enable azimuth and elevation movement of said antenna. 2. A system according to claim 1 wherein said fluid is water. 3. A system according to claim 1, wherein said fluid is heated water.

4. A s tern according to claim l, wherein sar fluid IS a predetermined mixture of water and an antifreeze solution.

5. A system according to claim 1 wherein said fluid is water, and said first reservoir is hurried below ground level at a sufficient depth to prevent freezing of said water.

6. A system according to claim 1, wherein said distribution system causes said fluid to be discharged from said plurality of noales under controlled pressure at a predetermined rate.

7. A system according to claim 1, wherein each of said plurality of nozzles include a spray nozzle.

8. A system according to claim 1, further including a second reservoir of said fluid, and an arrangement to replenish said fluid of said first reservoir with said fluid from said second reservoir at a given rate.

9. A snow and ice removal system for an antenna having a reflecting surface comprising:

a first reservoir of fluid;

a plurality of nozzles disposed adjacent said reflecting surface; and

a fluid distribution system connecting said first reservoir to said plurality of nozzles to supply said fluid to said plurality of nozzles;

said nozzles being appropriately disposed with respect to said reflecting surface and the flow of saidfluid in said distribution system being controlled to ensure that said reflecting surface is completely covered by said fluid discharged from said plurality of nozzles to thereby remove snow and ice from said reflecting surface;

said plurality of nozzles including five groups of three nozzles each equally disposed about the periphery of said reflecting surface and a sixth group of five nozzles disposed adjacent the center of said reflecting surface; and

said distribution system including a motor-pump assembly having a suction input and an output, a first 4 inch diameter galvanized pipe connected between said suction input and said first reservoir;

a second 4 inch diameter galvanized pipe connected to said output and extending to a point adjacent the bottom of said reflecting surface,

a flexible 4 inch diameter polyethylene pipe coupled to said second galvanized pipe and extending to a point adjacent the center of said reflecting surface, said flexible 4 inch pipe having sufficient slack to enable azimuth and elevation movement of said antenna,

a manifold constructed from 3 inch diameter galvanized pipe connected to said flexible 4 inch pipe,

six 1% inch diameter polyethylene pipes connected between said manifold and said six groups of nozzles, and

valves disposed in said manifolds and said six 1% inch pipes to control the pressure under which said fluid is discharged from each nozzles of said groups of nozzles. 

1. A snow and ice removal system for an antenna having a reflecting surface comprising: a first reservoir of fluid; a plurality of nozzles disposed adjacent said reflecting surface; and a fluid distribution system connecting said first reservoir to said plurality of nozzles to supply said fluid to said plurality of nozzles; said nozzles being appropriately disposed with respect to said reflecting surface and the flow of said fluid in said distribution system being controlled to ensure that said reflecting surface is completely covered by said fluid discharged from said plurality of nozzles to thereby remove snow and ice from said reflecting surface; and said distribution system including a portion of flexible pipe with sufficient slack to enable azimuth and elevation movement of said antenna.
 2. A system according to claim 1, wherein said fluid is water.
 3. A system according to claim 1, wherein said fluid is heated water.
 4. A system according to claim 1, wherein said fluid is a predetermined mixture of water and an anti-freeze solution.
 5. A system according to claim 1, wherein said fluid is water, and said first reservoir is burried below ground level at a sufficient depth to prevent freezing of said water.
 6. A system according to claim 1, wherein said distribution system causes said fluid to be discharged from said plurality of nozzles under controlled pressure at a predetermined rate.
 7. A system according to claim 1, wherein each of said plurality of nozzles include a spray nozzle.
 8. A system according to claim 1, further including a second reservoir of said fluid, and an arrangement to replenish said fluid of said first reservoir with said fluid from said second reservoir at a given rate.
 9. A snow and ice removal system for an antenna having a reflecting surface comprising: a first reservoir of fluid; a plurality of nozzles disposed adjacent said reflecting surface; and a fluid distribution system connecting said first reservoir to said plurality of nozzles to supply said fluid to said plurality of nozzles; said nozzles being appropriately disposed with respect to said reflecting surface and the flow of said fluid in said distribution system being controlled to ensure that said reflecting surface is completely covered by said fluid discharged from said plurality of nozzles to thereby remove snow and ice from said reflecting surface; said plurality of nozzles including five groups of three nozzles each equally disposed about the periphery of said reflecting surface and a sixth group of five nozzles disposed adjacent the center of said reflecting surface; and said distribution system including a motor-pump assembly having a suction input and an output, a first 4 inch diameter galvanized pipe connected between said suction input and said first reservoir; a second 4 inch diameter galvanized pipe connected to said output and extending to a point adjacent the bottom of said reflecting surface, a flexible 4 inch diameter polyethylene pipe coupled to said second galvanized pipe and extending to a point adjacent the center of said reflecting surface, said flexible 4 inch pipe having sufficient slack to enable azimuth and elevation movement of said antenna, a manifold constructed from 3 inch diameter galvanized pipe connected to said flexible 4 inch pipe, six 1 1/2 inch diameter polyethylene pipes connected between said manifold and said six groups of nozzles, and valves disposed in said manifolds and said six 1 1/2 inch pipes to control the pressure under which said fluid is discharged from each nozzles of said groups of nozzles. 